In February President Obama said, a little carelessly, that climate change is a greater threat than terrorism. Next week he will be in Paris, a city terrorized yet again by mass murderers, for a summit with other world leaders on climate change, not terrorism. What precisely makes these world leaders so convinced that climate change is a more urgent and massive threat than the incessant rampages of Islamist violence?

It cannot be what is happening to world temperatures, because they have gone up only very slowly, less than half as fast as the scientific consensus predicted in 1990 when the global-warming scare began in earnest. Even with this year’s El Niño-boosted warmth threatening to break records, the world is barely half a degree Celsius (0.9 degrees Fahrenheit) warmer than it was about 35 years ago. Also, it is increasingly clear that the planet was significantly warmer than today several times during the past 10,000 years.

Nor can it be the consequences of this recent slight temperature increase that worries world leaders. On a global scale, as scientists keep confirming, there has been no increase in frequency or intensity of storms, floods or droughts, while deaths attributed to such natural disasters have never been fewer, thanks to modern technology and infrastructure. Arctic sea ice has recently melted more in summer than it used to in the 1980s, but Antarctic sea ice has increased, and Antarctica is gaining land-based ice, according to a new study by NASA scientists published in the Journal of Glaciology. Sea level continues its centuries-long slow rise—about a foot a century—with no sign of recent acceleration.

Perhaps it is the predictions that worry the world leaders. Here, we are often told by journalists that the science is “settled” and there is no debate. But scientists disagree: They say there is great uncertainty, and they reflected this uncertainty in their fifth and latest assessment for the United Nations Intergovernmental Panel on Climate Change (IPCC). It projects that temperatures are likely to be anything from 1.5 to 4.5 degrees Celsius (2.7 to 8.1 degrees Fahrenheit) warmer by the latter part of the century—that is, anything from mildly beneficial to significantly harmful.

As for the impact of that future warming, a new study by a leading climate economist, Richard Tol of the University of Sussex, concludes that warming may well bring gains, because carbon dioxide causes crops and wild ecosystems to grow greener and more drought-resistant. In the long run, the negatives may outweigh these benefits, says Mr. Tol, but “the impact of climate change does not significantly deviate from zero until 3.5°C warming.”

Mr. Tol’s study summarizes the effect we are to expect during this century: “The welfare change caused by climate change is equivalent to the welfare change caused by an income change of a few percent. That is, a century of climate change is about as good/bad for welfare as a year of economic growth. Statements that climate change is the biggest problem of humankind are unfounded: We can readily think of bigger problems.” No justification for prioritizing climate change over terrorism there.

The latest science on the “sensitivity” of the world’s temperature to a doubling of carbon-dioxide levels (from 0.03% of the air to 0.06%) is also reassuring. Several recent peer-reviewed studies of climate sensitivity based on actual observations, including one published in 2013 in Nature Geoscience with 14 mainstream IPCC authors, conclude that this key measure is much lower—about 30%-50% lower—than the climate models are generally assuming.

A key study published in the Journal of Climate this year by Bjorn Stevens of the Max Planck Institute for Meteorology in Hamburg, Germany, found that the cooling impact of sulfate emissions has held back global warming less than thought till now, again implying less sensitivity. So the high end of the IPCC range is looking even more implausible in theory and practice. When politicians intone that, despite the slow warming so far, “two degrees” of warming is inevitable and imminent, remember they are using high estimates of climate sensitivity.

Yes, but if there is even a tiny chance of catastrophe, should the world not strain every sinew to head it off? Better to decarbonize the world economy and find it was unnecessary than to continue using fossil fuels and regret it. If decarbonization were easy, then sure, this would make sense. But the experience of the last three decades is that there is no energy technology remotely ready to take over from fossil fuels on the scale needed and at a price the public is willing to pay.

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About David H Lukenbill

I am a native of Sacramento, as are my wife and daughter. I am a consultant to nonprofit organizations, and have a Bachelor of Science degree in Organizational Behavior and a Master of Public Administration degree, both from the University of San Francisco.
We live along the American River with two cats and all the wild critters we can feed.
I am the founding president of the American River Parkway Preservation Society and currently serve as the CFO and Senior Policy Director.
I also volunteer as the President of The Lampstand Foundation, a nonprofit organization I founded in 2003.